A special adjusting frame for detecting the stress of a half-sphere harmonic oscillator and a detection method thereof

Abstract

A kind of special adjusting frame for hemispherical resonator coating stress detection and its detection method, the adjusting frame includes three-jaw chuck, axial and transverse rotary table, two-dimensional and three-dimensional displacement table and spectral confocal probe, can firmly hold resonator and realize its accurate adjustment and rotation in multiple dimensions, ensure that resonator and rotating shaft are concentric;Detection method includes using spherical interferometer to detect the surface shape of uncoated and coated resonator, adjusting the position of resonator by seven-dimensional adjusting frame, reconstructing complete surface shape using splicing algorithm, comparing the surface shape data before and after coating, and then calculating the stress of resonator by deduced stress and strain formula.The present application can directly detect the coating thermal stress of resonator, without damaging the resonator and film, and has high detection efficiency, while ensuring the accuracy of detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical detection, and specifically relates to a special adjusting frame for half-sphere resonator coating stress detection and a half-sphere resonator coating stress detection method. BACKGROUND

[0002] The components of the half-sphere resonator gyroscope are all processed from high-precision fused quartz glass to ensure low zero-bias stability in operation. However, in order to generate micro-vibration through electrostatic excitation, the half-sphere resonator gyroscope sealed in a vacuum container needs to be metalized and coated, so as to have good electrical conductivity.

[0003] The quality factor of the quartz glass material is expressed by Q value, which is an important performance index of the resonator acoustics and is closely related to the energy attenuation. The fundamental reason affecting the Q value of the half-sphere resonator is internal loss, i.e. energy loss phenomenon caused by various defects in the vibration process: internal loss caused by asymmetric distortion of face-centered cubic lattice structure, stress-induced ordered internal loss of substitutional atoms, grain boundary internal loss and dislocation internal loss. The uniformity of the metal thin film and the residual stress generated after coating will all bring internal loss. In this process, the residual stress brought by the metal thin film preparation process will reduce the quality factor Q value of the resonator to 20% to 30% of the Q value before coating. If the residual stress of the thin film after coating the half-sphere resonator shows a large tensile stress, the film layer is easy to crack; on the contrary, if it shows a large compressive stress, the film layer is easy to blister, thereby leading to failure of the thin film. Therefore, accurate measurement of the residual stress of the thin film is an urgent problem to be solved.

[0004] The existing stress measurement methods have obvious deficiencies. Traditional mechanical methods, such as adhesive method and scratch method, measure the stress value by completely releasing the residual stress, which will cause damage to the workpiece and is not suitable for high-precision half-sphere resonator gyroscopes. Physical measurement methods mainly include Stoney formula method, X-ray diffraction method and ultrasonic method. The Stoney formula method ingeniously measures the stress by measuring the strain through the curvature of the substrate, which is a measurement method not affected by the properties of the thin film; the X-ray diffraction method calculates the stress by measuring the change of the peak diffraction angle, which is a representative technology for non-destructive measurement of residual stress, but the X-ray diffraction and Stoney formula method cannot detect spherical components; the ultrasonic method uses the acoustic birefringence effect to obtain and calculate the average stress on the propagation path, which needs high-precision acoustic velocity measuring instruments and needs to measure the acoustic elastic characteristic values of the material in advance, which is another difficult problem. This method has not been put into practical measurement. New measurement methods mainly include the Barkhausen noise method, nuclear magnetic resonance method and Raman spectroscopy method. Generally, the experiment is complex, the equipment is expensive, the suitable measurement situations are limited, and the development is also slower.

[0005] In summary, the current residual stress measurement technology after the metal coating of the hemispherical resonator gyroscope has many limitations. Neither the traditional method nor the emerging technology can guarantee the measurement accuracy while considering non-destructive testing and wide applicability. This has become one of the key factors restricting the further improvement of the performance of the hemispherical resonator gyroscope, and it is urgent to conduct in-depth research and innovation breakthroughs in the industry. SUMMARY

[0006] The purpose of the present application is to provide a special adjusting frame for hemispherical resonator coating stress detection and a hemispherical resonator coating stress detection method. The special adjusting frame integrates a three-dimensional displacement table, a two-dimensional displacement table, and two rotating tables (axial and lateral orientation), achieving accurate adjustment of the resonator in multiple dimensions. The surface shape change of the resonator before and after coating is detected by a spherical interferometer, and the surface shape of the resonator after coating is detected, and then the thermal stress of the resonator coating is calculated using the hemispherical resonator stress calculation formula.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] On the one hand, the present application provides a special adjusting frame for hemispherical resonator coating stress detection, characterized in that it comprises:

[0009] A three-jaw chuck is used for self-centering, and the resonator is clamped by the stem to ensure that the resonator is concentric with the axial orientation rotating table;

[0010] The axial orientation rotating table is concentrically installed with the three-jaw chuck, allowing the resonator to rotate in the axial orientation;

[0011] A two-dimensional displacement table is installed on the lateral orientation rotating table for the axial orientation rotating table to be placed, and is used for the resonator to be adjusted to be concentric with the rotating shaft of the lateral orientation rotating table;

[0012] The lateral orientation rotating table is installed on the three-dimensional displacement table for the two-dimensional displacement table to be placed, allowing the resonator to rotate in the lateral orientation;

[0013] The three-dimensional displacement table is used for the lateral orientation rotating table to be placed, and is used for spatial three-dimensional positioning;

[0014] The spectral confocal probe 1 and the spectral confocal probe 2 measure the absolute position change of the resonator surface, and the two-dimensional displacement table is adjusted according to the measurement data, taking the rotating shaft as the origin, when rotating clockwise:

[0015] When the reading of the spectral confocal probe 1 decreases and the reading of the spectral confocal probe 2 decreases, the resonator sphere center is located in the first quadrant;

[0016] When the reading of the spectral confocal probe 1 decreases and the reading of the spectral confocal probe 2 increases, the center of the resonator sphere is located in the second quadrant;

[0017] When the reading of the spectral confocal probe 1 increases and the reading of the spectral confocal probe 2 increases, the center of the resonator sphere is located in the third quadrant;

[0018] When the reading of the spectral confocal probe 1 increases and the reading of the spectral confocal probe 2 decreases, the center of the resonator sphere is located in the fourth quadrant;

[0019] When the center of the resonator sphere coincides with the rotation axes of the lateral orientation rotation table and the axial orientation rotation table, the readings of the spectral confocal probe 1 and the spectral confocal probe 2 do not change significantly.

[0020] Further, the three-jaw chuck can firmly clamp the central rod of the resonator, and through the self-centering function, the center of the resonator sphere is preliminarily coincided with the rotation axis of the axial orientation rotation table.

[0021] Further, by rotating the lateral orientation rotation table and measuring the absolute position change of the resonator surface using the spectral confocal probe, the two-dimensional displacement table is adjusted according to the measurement data until the center of the resonator sphere coincides with the rotation axes of the lateral orientation rotation table and the axial orientation rotation table.

[0022] In another aspect, the application also provides a method for detecting the stress of a hemispherical resonator coating film using the special adjusting frame, which comprises the following steps:

[0023] S1. Detecting the surface shape of the uncoated resonator using a spherical interferometer;

[0024] S2. Fixing the resonator on the seven-dimensional adjusting frame, and adjusting the seven-dimensional adjusting frame so that all surfaces of the resonator can be detected by the spherical interferometer;

[0025] S3. After the measurement is completed, using a stitching algorithm to stitch the measured multiple sub-apertures to reconstruct the complete surface shape of the resonator before coating;

[0026] S4. Coating the resonator, and after the coating is completed, repeating the above steps to detect the surface shape of the coated resonator using the spherical interferometer and the seven-dimensional adjusting frame, and reconstructing the complete surface shape of the resonator after coating;

[0027] S5. Comparing the surface shape data before and after coating to calculate the change amount of the surface shape;

[0028] S6. Applying a hemispherical resonator stress calculation formula to measure the axial deformation of the resonator by the interferometer, and calculating the stress of the resonator according to the axial deformation.

[0029]

[0030] Where P is the film stress on the resonator, a is the angle corresponding to the arc length of the spherical shell, θ i The angle corresponding to the arc length of any point on the circular arc, R is the resonator radius, E is the Young's modulus, I is the cross-sectional moment of inertia, which is simplified as a square with the resonator wall thickness as the side length, y θ The axial deformation at angle θ, measured by the interferometer, i is the number of pixels measured by the interferometer in the axial direction.

[0031] Further, the step S2 specifically comprises:

[0032] Step S2.1 clamps the rod of the resonator on the three-jaw chuck and ensures that the resonator is concentric with the rotation table rotating in the axial direction;

[0033] Step S2.2 measures the absolute position change of the resonator surface using the optical spectrum confocal probe 1 and the optical spectrum confocal probe 2, adjusts the two-dimensional displacement table according to the measurement data, and takes the rotation axis as the origin, when rotating clockwise:

[0034] When the reading of the optical spectrum confocal probe 1 decreases and the reading of the optical spectrum confocal probe 2 decreases, the ball center of the resonator is located in the first quadrant;

[0035] When the reading of the optical spectrum confocal probe 1 decreases and the reading of the optical spectrum confocal probe 2 increases, the ball center of the resonator is located in the second quadrant;

[0036] When the reading of the optical spectrum confocal probe 1 increases and the reading of the optical spectrum confocal probe 2 increases, the ball center of the resonator is located in the third quadrant;

[0037] When the reading of the optical spectrum confocal probe 1 increases and the reading of the optical spectrum confocal probe 2 decreases, the ball center of the resonator is located in the fourth quadrant;

[0038] When the ball center of the resonator coincides with the rotation axis of the rotation table rotating in the axial direction and the rotation axis of the rotation table rotating in the lateral direction, there is no obvious change in the readings of the optical spectrum confocal probe 1 and the optical spectrum confocal probe 2.

[0039] Step S2.3 places the adjustment frame clamped with the resonator in the detection area of the spherical interferometer, and detects after adjusting the three-dimensional displacement table to make the interference fringes in the best state;

[0040] Step S2.4 rotates the rotation table rotating in the axial direction to detect all sub-apertures in this direction;

[0041] Step S2.5 after the detection is completed, rotates the rotation table rotating in the lateral direction to change the lateral direction, and then rotates the rotation table rotating in the axial direction to detect until all surfaces of the resonator are covered;

[0042] Preferably, the exit aperture of the spherical interferometer is 100 mm, and the F number of the spherical standard mirror is 1.

[0043] Compared with the prior art, the present application has the following advantages:

[0044] 1) The three-dimensional displacement table, two-dimensional displacement table, and two rotating tables (axial and lateral orientation) are integrated, realizing accurate adjustment of the resonator in multiple dimensions, improving the flexibility of adjustment, and ensuring the stability and accuracy of the resonator during detection. At the same time, by using a three-jaw chuck as a centering mechanism, the resonator can be firmly clamped, ensuring its concentricity with the rotating table of the axial orientation, effectively reducing measurement errors caused by improper clamping, and improving the detection accuracy. Combined with the use of a spectral confocal probe, real-time feedback can be provided during adjustment, helping users quickly and accurately complete the concentricity adjustment of the resonator and the rotating shaft.

[0045] 2) The spherical interferometer can be used to directly detect the spherical resonator without using the patch method, avoiding the conversion of the spherical surface to a planar surface for detection, and the resonator after detection can be directly used. Interferometric detection does not affect the plated resonator, is a non-destructive detection method, and has high detection efficiency. Using the interferometric detection principle, interferometric detection avoids the influence of contact with the measured part on the subsequent use of the measured part.

[0046] 3) During detection, the method uses sub-aperture stitching technology to stitch the measured sub-aperture to obtain the complete surface profile of the resonator before and after plating. Combined with the surface profile change before and after plating, the stress of the hemispherical resonator is calculated using the hemispherical resonator stress calculation formula, which can intuitively and accurately reflect the influence of the plating process on the stress of the resonator, providing strong support for quality control and performance optimization of the resonator. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 FIG. 1 is a perspective view of the special adjustment frame for hemispherical resonator plating stress detection of the present application;

[0048] Figure 2 FIG. 2 is a use state diagram of the special adjustment frame for hemispherical resonator plating stress detection of the present application;

[0049] Figure 3 (a) is a schematic diagram of eccentric rotation of the resonator.

[0050] Figure 3 (b) is a schematic diagram of deformation before and after plating.

[0051] Figure 4 (a) is a result diagram of stitching after interferometric measurement

[0052] Figure 4(b) is the result figure of the pre and post coating deformation obtained according to the splicing result.

[0053] Figure 5 The flow chart of the stress detection method for the hemispherical resonator coating.

[0054] In the figure: 1-interferometer; 2-spherical standard mirror; 3-resonator; 4-three-jaw chuck; 5-axial orientation rotating rotary table; 6-two-dimensional displacement table; 7-lateral orientation rotating rotary table; 8-three-dimensional displacement table; 9-spectral confocal probe 1; 10-spectral confocal probe 2. DETAILED DESCRIPTION

[0055] The application will be further described in detail below in combination with the drawings and examples, but the protection scope of the application should not be limited thereby.

[0056] Please refer to Figures 1-2 , Figure 1 It is a perspective view of the special adjusting frame for the hemispherical resonator coating stress detection of the application. Figure 2 It is a use state view of the special adjusting frame for the hemispherical resonator coating stress detection of the application. As shown in the figure, the special adjusting frame for the hemispherical resonator coating stress detection integrates multiple precision adjusting mechanisms to ensure the high-precision positioning and alignment of the resonator during the detection process. Specifically, it includes a three-jaw chuck 4 for centering, and an axial orientation rotating rotary table 5 concentrically installed with the three-jaw chuck 4, the rotary table 5 is installed on a two-dimensional displacement table 6; the two-dimensional displacement table 6 is installed on a lateral orientation rotating rotary table 7; the two-dimensional displacement table 6 is used for the rotation axis centering adjustment of the resonator 3 and the lateral orientation rotating rotary table 7, and the lowest layer is a three-dimensional displacement table 8 for the spatial three-dimensional positioning of the spherical interference detection.

[0057] Measurement process:

[0058] 1. Eccentricity measurement and adjustment:

[0059] After the resonator 3 is clamped by the three-jaw chuck, first rotate the rotary table that controls the lateral orientation of the resonator.

[0060] Use the spectral confocal probe to measure the absolute position of the resonator. Through the eccentricity measurement during the rotation process, it can be accurately judged whether the resonator exists eccentricity relative to the rotation axis.

[0061] According to the measurement data, adjust the two-dimensional displacement table to gradually reduce the clamping eccentricity until the required accuracy is reached.

[0062] 2. Adjustment of the coincidence of the resonator center and the rotation axis:

[0063] Take the center rod of the resonator as the positioning reference and clamp it on the three-jaw chuck to ensure that the spherical center of the resonator and the axial orientation rotating axis are preliminarily coincident.

[0064] Again, the absolute position of the resonator surface is measured using the spectral confocal probe, while the rotation stage in the lateral orientation is rotated.

[0065] Due to the existence of the eccentricity and the rotation stage in the lateral orientation, the absolute position measured by the spectral confocal probe will change. According to these changes, the eccentricity can be calculated, and the two-dimensional displacement stage is adjusted so that the center of the resonator and the rotation axis in the lateral orientation are completely coincident.

[0066] 3. Final adjustment before interferometric measurement:

[0067] The adjusted seven-dimensional adjustment frame (including the three-dimensional displacement stage, the two-dimensional displacement stage, the two rotation stages, and the three-jaw chuck) is placed in the detection area of the spherical interferometer.

[0068] By observing the interference fringes, the three-dimensional displacement stage is further adjusted until the zero-fringe state is reached, i.e., the surface of the resonator is completely parallel to the reference surface of the interferometer.

[0069] In this state, the sub-aperture detection is performed, and then the rotation stage is rotated to gradually complete the detection of the entire surface of the resonator.

[0070] Figure 5 The flowchart of the method for detecting the stress of the hemispherical resonator after coating is shown in the figure. The method includes the following steps: using the spherical standard mirror 2 equipped with the interferometer 1 to detect the surface shape of the resonator 3 before coating, placing the adjustment frame clamping the resonator 3 in the detection area of the spherical interferometer, adjusting the three-dimensional displacement stage 8 according to the fringes, and detecting after adjusting to the zero-fringe state. Rotating the rotation stage 5 in the axial orientation, detecting all sub-apertures in this orientation, rotating the rotation stage 7 in the lateral orientation after the detection is completed, rotating the rotation stage 5 in the axial orientation after changing the lateral orientation, and detecting until all surfaces of the resonator are covered. The measured sub-apertures are spliced to obtain the surface shape of the resonator 3 before coating. The resonator 3 is coated, and the above operation is repeated to obtain the surface shape of the resonator 3 after coating. The change in the surface shape of the resonator 3 before and after coating is obtained, the stress of the resonator is calculated using the hemispherical resonator stress calculation formula, and finally the stress change of the resonator 3 before and after coating is obtained.

[0071] In this embodiment, the exit aperture of the spherical interferometer is 100 mm, and the F number of the spherical standard mirror is 1. The resonator 3 is coated using the vacuum evaporation method, the vacuum degree is between 1.0 x 10 -3 pa-1.0 x 10 -4 pa, and the temperature is between 150°C and 250°C. The stress of the resonator is calculated using the hemispherical resonator stress calculation formula.

Claims

1. An interferometric measuring mechanism for measuring the axial deformation of a resonator, characterized in that, include: The three-jaw chuck (4) is used for self-centering and ensures that the resonator (3) is concentric with the rotary table (5) that rotates in the axial direction by clamping the rod of the resonator (3); A rotary table (5) that rotates in the axial direction is installed concentrically with the three-jaw chuck (4), allowing the resonator (3) to rotate in the axial direction; A two-dimensional displacement stage (6) is installed on a rotating stage (7) that rotates in the horizontal orientation, for the rotating stage (5) that rotates in the axial orientation, and for the alignment adjustment of the rotation axis of the resonator (3) and the rotating stage (7) that rotates in the horizontal orientation. A lateral rotation stage (7) is mounted on a three-dimensional displacement stage (8) for the two-dimensional displacement stage (6) to be placed, allowing the resonator (3) to rotate in the lateral direction; A three-dimensional displacement stage (8) is placed for the rotation stage (7) for lateral orientation rotation, and is used for aligning the spatial position of the harmonic oscillator during interferometry. When the spectral confocal probe 1 (9) and the spectral confocal probe 2 (10) are installed, they are aligned with the rotation axis. After the resonator (3) is installed, the absolute spatial position of the surface of the resonator (3) is detected, and real-time feedback is provided when adjusting the concentricity of the resonator (3) with the rotation axis. After adjustment, use an interferometer (1) equipped with a spherical standard mirror (2) to perform interferometric measurements, and substitute the measurement results into the stress formula of the hemispherical harmonic oscillator to calculate the stress of the hemispherical harmonic oscillator.

2. The interferometric measuring mechanism for measuring the axial deformation of a harmonic oscillator according to claim 1, characterized in that, The axial deformation of the harmonic oscillator is measured using an interferometer, and the stress of the harmonic oscillator is calculated based on the axial deformation, using the following formula: Where P is the membrane stress on the harmonic oscillator, α is the angle corresponding to the calculated total arc length of the spherical shell, and θ is the angle. i The angle corresponding to the arc length at any point on the arc, R is the radius of the harmonic oscillator, E is Young's modulus, I is the moment of inertia of the cross section, which is simplified here to a square with the wall thickness of the harmonic oscillator as its side length, y θ Let θ be the axial deformation at angle θ, measured by an interferometer, and i be the number of pixels measured by the interferometer along the axial direction.

3. The interferometric measuring mechanism for measuring the axial deformation of a harmonic oscillator according to claim 1, characterized in that, By rotating the transverse orientation rotary stage (7) and measuring the absolute position change of the surface of the harmonic oscillator (3) using the spectral confocal probe 1 (9) and spectral confocal probe 2 (10), the two-dimensional displacement stage (6) is adjusted according to the measurement data, with the rotation axis as the origin. When rotating clockwise: When the reading of the confocal spectral probe 1 (9) decreases, the center of the sphere of the harmonic oscillator (3) is located in the first quadrant. When the reading of the confocal spectral probe 1 (9) decreases and the reading of the confocal spectral probe 2 (10) increases, the center of the sphere of the harmonic oscillator (3) is located in the second quadrant. When the reading of spectral confocal probe 1 (9) increases, the center of the sphere of the harmonic oscillator (3) is located in the third quadrant. When the reading of the confocal spectral probe 1 (9) increases and the reading of the confocal spectral probe 2 (10) decreases, the center of the sphere of the harmonic oscillator (3) is located in the fourth quadrant. When the center of the sphere of the resonator (3) coincides with the rotation axis of the transverse azimuth rotary table (7) and the axial azimuth rotary table (5), the readings of the spectral confocal probe 1 (9) and the spectral confocal probe 2 (10) show no significant change.

4. A method for detecting the coating stress of a hemispherical resonator using the interferometric measuring mechanism for measuring the axial deformation of a resonator as described in any one of claims 1-3, characterized in that, Including the following steps: S1. The surface profile of the uncoated harmonic oscillator is detected using a spherical interferometer; S2. Fix the resonator on the seven-dimensional adjustment frame, and adjust the seven-dimensional adjustment frame so that all surfaces of the resonator can be detected by the spherical interferometer; S3. After the measurement is completed, the multiple sub-apertures measured are spliced ​​together using a splicing algorithm to reconstruct the complete surface shape of the resonator before coating. S4. Coating the resonator. After coating, repeat the above steps. Using the methods of steps S1 and S2, use a spherical interferometer and a seven-dimensional adjustment frame to detect the surface shape of the coated resonator and reconstruct the complete surface shape of the coated resonator. S5. Compare the surface profile data before and after coating, and calculate the change in surface profile; S6. The stress of the hemispherical harmonic oscillator is calculated by substituting the actual measured surface changes into the stress calculation formula of the hemispherical harmonic oscillator.

5. The method for detecting coating stress of a hemispherical harmonic oscillator according to claim 4, characterized in that, Step S2 specifically includes: Step S2.1 Clamp the rod of the resonator (3) on the three-jaw chuck (4) and ensure that the resonator (3) is concentric with the axially rotating rotary table (5); Step S2.2 Use a spectral confocal probe (9) to detect the absolute spatial position of the surface of the harmonic oscillator (3), and rotate the lateral rotation stage (7) to observe the change in the spatial position of the surface of the harmonic oscillator. Adjust the two-dimensional displacement stage (6) according to the detection results until the spatial position of the surface of the harmonic oscillator (3) does not change significantly during rotation, and complete the concentric adjustment. Step S2.3 Place the adjustment frame holding the resonator (3) in the detection area of ​​the spherical interferometer (1), and perform detection after adjusting the three-dimensional displacement stage (8) to make the interference fringes reach the optimal state; Step S2.4 Rotate the rotating table (5) in the axial orientation to detect all sub-apertures in that orientation; After step S2.5 is completed, rotate the lateral rotation table (7) to change the lateral orientation, and then rotate the axial rotation table (5) to perform the test until all surfaces of the harmonic oscillator are covered.

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